The present invention relates generally to burglar alarms which generate a warning or alarm in response to unwanted intrusion. More specifically, the present invention relates generally to concealed burglar alarms typified by concealable sending units associated with windows to be monitored.
In the prior art a variety of approaches have been taken in the alarm technology to provide a warning against unauthorized intrusion. In general terms, such burglar alarms are adapted to sound a warning which may frighten away a surprised intruder, suitably alert the potential victim, or both. Usually such alarms tend to be bulky, difficult to operate, and in many cases, they are easily detected by professional thieves prior to effectuation of an unauthorized entry.
In the prior art a variety of sending units associated with such alarms have been proposed and it is known to provide magnetic reed switches for detecting unauthorized movement of windows, doors, or the like, whereby to generate a remote alarm. In U.S. Pat. No. 3,986,183 a burglar alarm generates a sound in response to the relative displacement of two magnets. A set and reset system is employed. U.S. Pat. No. 4,275,391 employs a pendulum with an attached magnet for effectuating an initial alarm. U.S. Pat. No. 4,292,629 is adapted to generate a signal through an electrical switch responsive to unauthorized displacement of a sliding glass door or screen door combination.
U.S. Pat. No. 3,706,090 issued to Callaghan on Dec. 12, 1972 is the closest art known to me. The burglar alarm of the aforesaid patent is for use on a window and it is activated by the breaking of a magnetic circuit across the window. However, I have found that with devices of the latter nature, professional thieves may easily discover them, and once the presence of such an alarm system is known by the would-be burglar, various routine acts of sabotage may be employed to gain unauthorized entry. Magnetic switches are also employed in the alarm systems of U.S. Pat. Nos. 4,438,430; 3,975,723; 4,160,972; 4,209,777 and 3,710,369.
The use of prior art burglar alarms known to me can be very difficult for the home consumer. For example, it is often very difficult to properly orient the sending unit in a convenient place which is easily accessible by the installer, but which is difficult to reach or circumvent by a burglar. Moreover, it is often difficult to associate some form of linkage member or the like with the window pane, the breakage or removal of which should activate the alarm system. Moreover, it will be readily apparent to those skilled in the art that alarm systems are normally disabled intentionally by the owner or user at a variety of times. For example, when it is desired to open various windows during cleaning or the like, the alarm should be temporarily disabled. This may occur during seasonal changes of the year, which may necessitate installation and subsequent removal of storm windows and the like.
In many prior art devices known to me, the system is deactivated electronically rather than mechanically. In other words, many times the consumer must actually adjust or disable the electronic units associated with the burglar alarm. I have found that it is much easier to simply disable the moving mechanical linkages. While many consumers can quickly grasp the operational concepts involved in a moving linkage, for example, many consumers have a great deal of difficulty in properly adjusting the associated electronic circuitry.
Hence, it would seem desirable to provide an easily concealable burglar alarm system which quickly and reliably detects intrusion through windows, but which may be conveniently disabled only by the user and without adjustment to associated electronic control circuitry.